Rock drill



April 7, 1936.

L. c. BAYLES ROCK DRILL Filed Deb. 2a, 1933 INVENTOR.

HIS ATTORNEY Lewis 613a Patented Apr. 7, 1936 UNITED STATES PATENT OFFICE ROCK DRILL tion of New Jersey Application December 28, 1933, Serial No. 704,262

6 Claims.

This invention relates to rock drills, and more particularly to rock drills of the fluid actuated type in which the air compressed by the piston in the ends of the piston chamber finds access 5 through the passages in the rock drill to the source of the pressure fluid whereby the percussive element of the rock drill is actuated.

One object of the invention is to prevent reversal of flow of the pressure fluid during its passage from a source to the distributing element of the rock drill.

Another object is to utilize the energy of the air compressed by the piston for effecting a speedy reversal of the piston in the ends of the piston chamber.

Other objects will be in part obvious and in part pointed out hereinafter.

In the accompanying drawing illustrating one form which the invention may assume in practice and in which similar reference numerals refer to similar parts,

' Figures 1 and 2 are longitudinal elevations, in section, of a rock drill having the invention applied thereto and showing the movable elements in certain positions which they will assume in operation, and V Figure 3 is a transverse view taken through Figure 1.

Referring more particularly to the drawing, 20 designates, in general, a rock drill comprising a cylinder 2| having a piston chamber 22 for the accommodation of a reciprocatory hammer piston 23. In addition to its function of imparting blows of impact to a working imple- 35 ment (not shown), the piston also serves to control an exhaust port 24 through which the pressure fluid actuating the piston is exhausted to the atmosphere.

In the rear end of the cylinder 2! is an en-.

40 larged bore 25 for the accommodation, among other elements, of rotation mechanism 26 and distributing valve mechanism 21, the latter being disposed adjacent the rear end of the piston chamber 22.

45 The distributing valve mechanism comprises,

in the present instance, a plate 28, in the bot-- 551 The rotation mechanism 26 may be of a well known type, as illustrated, and comprises a rifle bar 34 wherewith the piston 23 is slidably interlocked. The rifle bar carries the usual head 35 seated upon the plate 29, and in the head 35 are pawls 36 for engagement with the teeth 31 of a ratchet ring 38 which encircles the head 35 and rests upon the plate 29.

A closure is provided for the rear end of the bore 25 by a plate 39 attached to a back head 40 which constitutes the rearmost casing part of the rock drill and may be secured to the cylinder 2| in any suitable mamier. The back head 40, in the present instance, serves as a housing for a throttle valve 4| of the rotary type having a central chamber 42 which may be in constant communication with a source of pressure fluid supply.

In the wall of the throttle valve is a port 43 adapted to register with a passage 44 in the back head and leading to a supply reservoir 45 also in the back head. The reservoir 45 is preferably of annular shape and communicates with the valve chamber 30 through supply passages 46 arranged in the elements lying in the bore 25 between the supply reservoir 45 and the valve chamber 30.

In accordance with the practice of the invention means are provided to prevent the flow of air compressed by the piston through the passages in the rock drill and thus to the element, such as a hose or conduit 41, whereby pressure fluid is conveyed from a source of supply to the rock drill. The means selected for illustrative purposes comprises a valve 48 in the form of an annular plate reciprocable in a valve chamber 49 in the rear end of a plate 50 interposed between the ratchet ring 38 and the plate 39.

The rear and front surfaces of the valve 48 constitute actuating areas 5| and 52 of which the actuating area 5| in one position of the valve 48, seats against the plate 39 to cover the ends of those portions of the supply passages 46 lying within the plate 39. A seat 53 is provided for the actuating area 52 by the end surface of an annular rib 54 on the plate 50. On the inner and outer sides of the rib 54 are annular passages 55 and 56, respectively, both of which communicate with the supply passages 46.

A guide member 51 interposed between the plates 59 and 39 engages the inner surface of the valve 48 to guide said valve which is adapted to slide on the guide member and in the periphery of the guide member are recesses or notches 58- through which pressure fluid flows around the inner edge of the valve 48.

The operation of the device is as follows: Upon the'introduction cf pressure fluid into the rock drill and with the piston 23 in the rear end of the piston chamber, pressure fluid passing through the pasages 4B and acting against the actuating area 5| will throw the valve 48 against the seating surface, 53. The pressure fluid then flows over the inner and outer edges of the valve 48*and into the valve chamber 3!). With the valve 3| in the position illustrated, wherein it uncovers the rear inlet passage 33, pressure fluid flows into the rear end of the piston chamber and actuates the piston 23 forwardly on its working stroke.

As the piston proceeds forwardly, and after it covers the exhaust port 24, the air in the front end of the piston chamber 22 will be compressed by the piston and such compression wfll flow through the inlet passage 32 against the seated wing of the valve 3|. at about. the time the rear end of the piston uncovers the exhaust port 24 to communicate the rear end of the piston chamber with the atmosphere the pressure fluid flowing over the raised end of the valve and the compression, acting against the opposite end of the valve will tilt the valve 3| toits other limiting position. The compression,,loeing in excess of line pressure, will then upon striking the valve 48 momentarily close said valve. The air compressed by the piston 23 will thus be confined in the front end, of the piston chamber and in the passages communicating said. front end with the valve chamber 49.

As will be readily appreciated, if the compression generated ,by the piston 23 is of a value superior to thatrof the pressure fluid in the supply reservoir 45 the compressed medium forwardly of the piston will, upon expanding, cause a prompt reversal of the piston '23 and thus start it on its reverse stroke. Upon expansion of the compression forwardly of the piston to a value slightly below line pressure the pressure fluid acting against the actuating surface 5| will again move the valve 48 to the seating surface 53 andpressure fluid will then flow uninterruptedly from the supply reservoir 45 over the inner and outer edges of the valve 48, thence through the passages 46 into the valve chamber 30. From the valve chamber 30 the pressure fluid flows over the raised end of the valve through the inlet passage 32 into the front end of the piston chamber to continue the rearward movement of the piston 23. r a 7 After the piston again covers the exhaust port 24 the air entrapped in the rear end of the piston chamber is compressed and at the instant the piston uncovers the exhaust port 24 the suction caused by the air flowing over the raised end of the valve 3| into the inlet passage 32, together with the compression acting against the opposite wing of the valve 3|, will tilt the valve and compression then flows from the rear end of the piston chamber through the passages connecting it with the valve chamber 49. Upon reaching .the valve chamber 49 such compression will act against the actuating area 52' and move the valve 48 against the plate 39, thus momentarily cutting oif communication between the supply reservoir 45 and the rear end of the piston chamber.

As during the forward stroke of the piston the air compressed in the rear end of the piston chamber 22 will, upon expansion, reverse the travel of the piston 23. When the air compressed by the piston has expanded to a value slightly below line pressure the pressure fluid acting flow of pressure fluid into the valve chamber g 30, whence it passes over the raised end of the valve 3| through the inlet passage 32 into the front end of the piston chamber to complete the rearward stroke of the piston 23 a As will be readily apparent, by interposing the valve 48 between the piston chamber and the source of pressure fluid supply the air compressed in the piston chamber by the piston 23 will be restrained fromlentering the pressure fluid supply line, The course of the pressure fluid through the supply line,will thus be uni-directional instead of being reversed by the compression and the value of the pressure fluid admitted into the piston chamber will, by reason of that, fact, be uniform.

A further desirable advantage of the present invention is that in such instances as where the atmospheric air entrapped in the ends'of the piston; chamber and compressed by the piston reaches a value far in excess of line pressure the power-stored in such compression may be advantageously utilized for effecting a speedly reversal of the piston.

I claim: 7

1. In a fluid actuated rock drill, the combination of a cylinder having a piston chamber and a piston therein, a valve chamber, a valve in the valve chamber for distributing pressure fluictto the piston chamber and being controlled by the piston, a pressure fluid supply chamber, and means in the rock drill for preventing the flow of compression from the piston chamber to the pressure fluid supply chamber. V

2. In a fluid actuated rock drill, the combination of a cylinder having a piston chamber and a piston therein, means controlled by the piston for controlling the flow of pressure fluid from a source of supply to the piston chamber, a pressure fluid supply chamber, and means in the rock drill actuated by compression for preventing the flow of compression from the piston chamber to the supply chamber.

3. In a fluid actuated rock drill, the combination of a cylinder having a piston chamber and a piston therein, a valve chamber, a pressure fluid supply chamber in the rock drill, a supply passage in the rock drill for conveying pressure fluid from the supply chamber to the valve chamber, inlet passages for conveying pressure fluid from the valve chamber to the piston chamber, a valve in the valve chamber to control the inlet passages and being actuated by compression from the piston chamber, and means in the supply passage actuated compression from the piston chamber for preventing the flow of compression from the piston chamber to the supply chamber.

4. In a fluid actuated rock drill, the combination of a cylinder having a piston chamber and a piston therein, a valve chamber, pressure fluid supply chamber in the rock drill, a supply passage in the rock drill for conveying pressure fluid from the supply chamber to the valve chamber, inlet passages for conveying pressure fluid from the valve chamber to the ends of the piston chamber, a valve in the Valve chamber to control the inlet passages and being actuated by compression from the piston chamber, and valve means between the valve ehamber and the supply chamber actuated by compression for preventing the flow of compression from the piston chamber to the supply chamber.

l 5. In a fluid actuated rock drill. the combination of a cylinder having a piston chamber and a piston therein, a plurality of valve chambers in the rock drill, a pressure fluid supply chamber in the rock drill, a supply passage in the rock drill affording communication between the valve chambers and the pressure fluid supply chamber, a distributing valve in one valve chamber to control the distribution of pressure fluid to the piston chamber and being controlled by the piston, and a valve in another valve chamber to prevent the flow of compression from the piston chamber to the pressure fluid supply chamber.

6. In a fluid actuated rock drill, the combination of a cylinder having a piston chamber and a piston therein, a plurality of valve chambers in the rock drill, a, pressure fluid supply chamber in the rock drill, a supply passage in the rock drill aifording communication between the valve chambers and the supply chamber, a distributing valve in one valve chamber to control the distribution of pressure fluid to the piston chamber and being controlled by the piston, and a valve in another valve chamber actuated to one limiting position by pressure fluid to permit the flow of pressure fluid to the distributing valve and being actuated to another limiting position by compression from the piston chamber to prevent the flow of compression to the supply chamber.

LEWIS C. BAYLES. 

